Gas turbine engines, such as turbofan gas turbine engines, may be used to power various types of vehicles and systems, such as aircraft. Typically, these engines include turbines that rotate at a high speed when blades (or airfoils) extending therefrom are impinged by high-energy compressed air. Consequently, the blades are subjected to high heat and stress loadings which, over time, may reduce their structural integrity.
To improve blade structural integrity, a blade cooling scheme can be included to provide active cooling of the blade and to maintain the blade temperatures within acceptable limits. In some cases, the blade cooling scheme directs cooling air through an internal cooling circuit formed in the blade. The internal cooling circuit may include a simple channel extending through a length of the blade or may consist of a series of connected, serpentine cooling passages, which incorporate raised or depressed structures therein. The serpentine cooling passages increase the cooling effectiveness by extending the length of the air flow path. In this regard, the blade may have multiple internal walls that form intricate passages through which the cooling air flows to feed the serpentine cooling passages.
As the desire for increased engine efficiency continues to rise, engine components are increasingly being subjected to higher and higher operating temperatures. For example, newer engine designs may employ operating temperatures that produce turbine blade tip temperatures that exceed 1150° C. which may be 140° C. hotter than blade tip operating temperatures of current engines. However, current engine components, such as tips or parapets (also known as “tip cap”) of the blade, may not be adequately designed to withstand such temperatures over time. In particular, the tips or parapets of the blade may not include active cooling and may become hotter than surrounding portions of the blade. Hence, designs for improving the blades may be desired.
Accordingly, it is desirable to have an improved turbine blade that is suitable for use in operating temperatures greater than 1150° C. In addition, it is desirable for the improved turbine blade to be relatively simple and inexpensive to manufacture. Furthermore, other desirable features and characteristics of the inventive subject matter will become apparent from the subsequent detailed description of the inventive subject matter and the appended claims, taken in conjunction with the accompanying drawings and this background of the inventive subject matter.